*BSD News Article 81516


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From: Frederic.Marand@osinet.fr (Frederic MARAND)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: whats a good external SCSI tape?
Date: Thu, 24 Oct 1996 17:41:06 GMT
Organization: Groupe SEDI / Agorus SA / OSI SARL
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j@uriah.heep.sax.de (J Wunsch) wrote:

>Frederic.Marand@osinet.fr (Frederic MARAND) wrote:

>> >Tandberg 2.5 GB QIC are fine (the latter is for those like me who find
>> >helical scan to be inherently horrible :).

>> It seems many  people dislike helical scan backup units, but I never
>> could figure out why: ...

>Because the mechanics are much more fragile _by design_.  I've seen
>jamming tape cartridges that self-destroyed the tape on exertion, for
>example (on an otherwise fine working) HP-DAT drive.
Never seen that, and we sold tens of them. But thinking of the
mechanism used, it must be a matter of luck on our side, I'm afraid :
it DOES fell fragile.

>Also, helical scan drives are told to have a higher abrasion rate, so
>you ought to throw away a cassette after 50 or 100 hours.  This partly
>compensates for them being cheaper than e.g. QIC.
This is interesting: I'd never heard of it, but as a matter of fact,
tape manufacturers tended to recommend no more than 12 writes on DDS2
cartridges when they started producing them. You explanation might
justify this strange recommendation from 3M and others.

Now, about the other person talking about incompatibility problems, I
have to say I met them on QIC streamers : it took years before media
produced on a Sun (Archive drive, I guess) could be read on a HP (HP
drive, I guess). I think I remember they didn't record in the same
direction, which prevented any sort of software solution. Some of our
customers have several DATs (both HP and Conner now) on several sites
and routinely use mailed DAT tapes to exchange data between their
sites. 

Also, one african customer exchanges tapes between two Exabytes, one
of Wang brand, the other of IBM brand, but both of them Exabytes 820x
inside, and we never had any trouble with these either.

The other problem I had of the same sort was with floppy disks on
Atari ST: the same drive could not read its own floppies some months
after writing them. And here too, it happened with several drives....

-------------------------
   Frederic G. MARAND
  Agorus SA / OSI SARL
Frederic.Marand@osinet.fr
-------------------------